This patch enables the Silicon Image 3512 SATA Controller and has been tested and functioning without any apparent bugs (I do not have a full test suite but I am not booting off a device attached to this controller). This patch is against the Dave Jones 2.6.1-1.34 kernel source rpm.
You may remember I was trying to get help on this chipset before. My patch is simply a duplicate of the entries for the 3112 chipset. It did not work fully with prior kernels, giving me a "Interrupt Lost" errors. Whatever else was done to 2.6.1 had made it happy again. Also I did not have to use any special commandline options.